Chronic Obstructive Pulmonary Disease
(COPD)

Topic Highlights

●    COPD is a group of respiratory diseases involving obstruction of the airways, including chronic bronchitis and emphysema.

●    Chronic bronchitis results in swelling and excess mucus production in airways while emphysema causes permanent enlargement of air sacs.

●    This visual presentation describes the respiratory system, occurrence of COPD, causes, symptoms, diagnosis, and treatment.

Transcript

Chronic Obstructive Pulmonary Disease or COPD is a group of diseases that affects the lungs causing difficulty in breathing. It affects millions of people worldwide and is the fourth leading cause of death in the world, following heart diseases, pneumonia and HIV/AIDs. According to the World Health Organization(WHO), the worldwide prevalence of COPD in 2002 was 11.6 cases per 1,000 men and 8.77 cases per 1,000 women. In 2004, there were 2.75 million deaths due to COPD worldwide, of which 1.41 Million were men and 1.34 Million were women.

COPD is a group of diseases that affect the lungs and the airways, that worsen progressively and limit the patient's ability to breathe. It includes conditions like chronic obstructive bronchitis and emphysema.

Respiration is a process by which oxygen is taken in and carbon dioxide is expelled from the body. This function is performed by the respiratory system which consists of the nose, nasopharynx, larynx, trachea, bronchi and lungs. When the muscles of the diaphragm and the rib cage contract, the lungs expand, resulting in negative air pressure in the lungs. This causes the air from outside to enter through the nose. The inner lining of the nose has fine hairs called cilia that filter the air and prevent particulate matter from entering the respiratory tract.

The air then passes through the nasopharynx, which is at the back of the mouth and then goes through to the larynx. The larynx has a valve called the epiglottis that opens to let air pass through to the trachea, and closes to prevent food from the mouth entering into the respiratory tract. The trachea is a tube that has cartilage rings connected by muscle. The trachea goes down the neck and branches into two, one going into each lung. The branches of the trachea are called bronchi.

The trachea and the bronchi are lined with two types of cells. One set of cells has hair-like projections that filter the air as it passes and the other type of cells secrete a sticky liquid called mucus. The mucus helps in trapping particulate matter from the air and pushes them out of the respiratory tract via coughing. The right and the left bronchi enter their respective lungs through the hilum. After entering the lungs the bronchi further divide to form bronchioles.

Each bronchiole has many microscopic alveolar ducts and atria that open in a bag like structure called the alveolus. This is called a pulmonary unit. The lungs are made up of many such pulmonary units. The inhaled air reaches the alveoli after passing through the trachea and bronchi. A dense network of blood vessels surrounds the alveoli. Oxygen from the air is absorbed by the hemoglobin in the blood and carried to the tissues in our body. In the body tissues, the hemoglobin releases the oxygen and picks up the carbon dioxide and brings it via the blood to the alveoli. The carbon dioxide from the hemoglobin is released and oxygen is absorbed again thereby continuing the cycle.

When the muscles in the diaphragm and the rib cage relax and cause the lungs to collapse, the carbon dioxide is squeezed out of the lungs up into the trachea and the nose, to the outside. The alveoli secrete proteins that help in weakening and destroying micro-organisms that may have reached the lungs along with air that is breathed in. The blood vessels lining the alveoli also release cells called macrophages that identify micro-organisms or foreign matter in the lungs and engulf and destroy them.

The leading cause of COPD is smoking. More than 15% of all chronic smokers will develop COPD. In rare cases COPD is inherited and is caused by a deficiency in Alpha-1 antitrypsin in the body.

The other risk factors for COPD are recurrent respiratory infections, exposure to second hand smoke, air pollution, and poor nutrition, especially deficient in antioxidant Vitamins A, C and E. Older women are more prone to COPD, and the incidence of COPD in younger women is now rising due to a recent increase in cigarette smoking among women. Persons working at construction sites, in coal mines and metal industries are also at risk.

COPD is a group of diseases that include chronic obstructive bronchitis and emphysema. Thus the pathogenesis of COPD can be explained by the pathophysiology of these conditions. Continuous irritation of the respiratory tract by inhaled particles of cigarette smoke or other pollutants causes inflammation of the bronchi and bronchioles, resulting in chronic obstructive bronchitis. The inflammation and swelling lead to scarring and narrowing of the small airways making it more difficult to breathe.

Long term exposure to cigarette smoke or air pollutants can also cause excessive production of enzymes called elastases in the lungs, which leads to a break down of lung tissue. As a result, the walls between individual alveoli become perforated and larger air spaces are created. Emphysema results from this permanent enlargement of the alveoli making the lungs lose elasticity and collapse. This disturbs normal airflow in and out of the lungs, making breathing difficult.

Shortness of breath on exertion is the major symptom of COPD. The diagnosis of COPD is made based on medical history and symptoms. Other investigations that are done to confirm the diagnosis are pulmonary or lung function tests that determine the amount of airway obstruction and capacity of the lung; chest X-rays; CT scan of the chest; blood gas analysis which shows the concentration of oxygen and carbon dioxide in the blood and sputum analysis to check for infection.

There is no cure for COPD because lung tissue and scarring of the airways are irreversible. However, appropriate management of the disease will help alleviate the symptoms and prevent further damage to the lungs. If smoking is the cause for COPD, the patient is advised to quit smoking completely. Antibiotics may be prescribed to treat infections of the respiratory tract, which are very common in COPD patients. Vaccination for influenza and pneumonia are advised at regular intervals to prevent against their attacks.

Other medications that are prescribed to alleviate symptoms include bronchodilators, anti-cholinergics and corticosteroids. Bronchodilators dilate the airways by relaxing the muscles of the airways thereby increasing the lumen and reducing airflow obstruction. Bronchodilators are long acting. Examples are long-acting beta2-agonists like salmeterol and formoterol or a long-acting anticholinergic, tiotropium, block the action of acetylcholine, the naturally occurring neurotransmitter that leads to contraction of muscles in the airways; thus relaxing the bronchial muscles and improving air flow.

Corticosteroids like fluticasone and budesonide can be given as inhalation. They help reduce inflammation and swelling and clear the airways. They are usually combined with bronchodilators. Steroid tablets are only used for exacerbations, whereas steroid inhalers are used in some patients with more severe disease.

Oxygen therapy provides external supplementation of oxygen in long-term COPD patients, whose oxygen levels have significantly depleted. Surgery that involves removal or resection of the damaged portion of the lung may help in improving lung function in certain cases. Lung volume reduction surgery is only appropriate for highly selected patients. In very severe cases, a lung transplant may be an option.

Smokers with COPD should stop smoking completely and immediately. Aids to quit smoking include nicotine replacement such as chewing gum or skin patches or some medications that are prescribed by the doctor. Avoid polluted places and irritants that cause flare-up in symptoms. Respiratory infections should be reported and treated immediately. Exercise regularly. Drink 8 to 10 glasses of water daily to keep the mucous secretions thin and easy to cough out. Eat a well-balanced and healthy diet.

Patients should learn breathing techniques to increase the capacity of lungs. Lie down with head on pillow, place hands on chest and feel diaphragm. Breathe deeply through the mouth and feel diaphragm rise. Hold the breath for a count of three. Then exhale through mouth until a count of six. Repeat the exercise 10 times.